And nathaniel m



(No Model.)

C. CURTIS & N. M. JONES. BAPER PULP DIGESTER.

UNiTEn STATES PATENT' OFFICE..

CHARLES CURTIs, OE NEWTON, MASSACHUSETTS, AND NATHANIEL M. JONES, OE BANGOR, MAINE.

PAPER-PU LP DIGESTER.

SPECIFICATION forming part of Letters Patent No. 484,999, dated October 2.5, 1892.

Application Ailed December 19, 1891. Serial No. 415,656. (No model.) i

To all whom t may concern.-

Be it known that we, CHARLES CURTIS, of Newton, in the county of Middlesex and State of Massachusetts, and NATHANIEL M. JONES, of Bangor, in the county of Penobscot and State of Maine, have invented certain new and useful improvements in Paper-Pulp Digesters, of which the following is a specification.

This invention relates to digesters for cooking wood chips in the manufacture of paperpulp, and has for its object to provide such a construction as will protect the metal shell of the digester against the acid solutions em ployed to dissolve the resins and gums of the Wood.

To these ends the invention consists in the pulp-digester comprising the construction as hereinafter described and claimed.

Of the accompanying drawings, forming part of this specification, Figure 1 represents a side elevation, partly in section, of a digester provided with my improvements. Fig. 2 represents a section on line 2 2, Fig. 1. Fig. 3 represents a vertical section of the bottom portion of the dgester. Fig. 4 represents a partial horizontal section showing the lining made in one thickness or layer.

The same letters and numerals of reference indicate the same parts in all the figures.

In the drawings, a represents the shell of a digester, which is preferably of cylindrical form and composed of any suitable metal, such as iron, steel, phosphor-bronze, brass, &c. We prefer to make the shell of plates having butt-joints, the edges of the plates abutting against each other instead of overlapping, and being held by external plates or bands o', to which the plates are riveted. This construction gives the shell a smooth interior, free from projections, and enables the intermediate and cement lining, hereinafter described, to be closely fitted to the interior of the shell. v

b represents an intermediate lining, which is preferably composed of asbestus and cement made into a plast-ic composition and applied to the inner surface of the shell in a plastic state, its object being to protect the inner cement lining, hereinafter described, and to prevent contact of the acid solution with the metal shell in the event of leakage through the cement lining.

c represents the cement lining, which is composed, preferably, of Portland cement and ground glass or quartz, with or without a percentage of soluble glass. XVe do not limit ourselves to this composition, however, and may use any other cement or composition.

XVe show the cementlining as constructed in sections 8 S, which are provided at their edges with tongues 9 and recesses 10, the tongues of each section entering the recesses of the adjacent sections, so that the sections overlap at their joints. We prefer to form on the back sidefof each tongue 9 a rib or projection l2, enteringa correspondinggroove 13 in the surface of the recess 10, int-o which the tongue 9 enters. The inner surfaces of the sections 8 8 are provided with recesses 14 14, which collectively form a dovetail recess extending in both directions from the seam between each section and adapted to receive a packing or joint-covering strip 15 of lead, cement, or any other suitable material. To prefer to interpose packings between the surfaces of the tongues 9 and recesses 10, said packings being either of lead or cement.

It will be seen that the joint-coverings 15, the tongues 9, the recesses 10, and the packings between said tongues and recesses make the joints between the diii'erent sections extremely secure and reduce to the minimum the liability of the acid solution Iinding its way through the cement lining, To further reduce this liability we may make the cement lining in two layers, as shown in Figs. 1, 2, and 3, each layer being composed of sections formed as above described, the joints of the sections composing the inner layer alternating with those of the sections composing the outer layer, as'shown in Figs. 1 and 2, so that in the event of leakage between the joints of the sections of the inner layer the acid would meet a solid portion ofthe outer layer. We do not limit ourselves to the particular form of the meeting edges of the sections here shown, but may give said sections any other suitable form, and provide any other suitable means for packing and making acidproof joints.

In Fig. 3 we show the lining of the bottom of the digester as formed in one piece; or,

IOO

rather, each layer: of said lining is formed-l in onev piece, said pieces fitting the shape of the shell at the bottom of the dgester. The inner layer of the bottom lining has a recess at its upper edge to receive the lowerpart of a packing or joint-covering 15, which coversthe joint between the inner layer of'tlie bottom-lining and the bottom sections of the inner layer of the lining of the body of the digester. The outer layer of the bottom-lining is shown as provided with a tongue 9 of the form above described, fitting the recess 10 in the lower end of the outer layer-"of the lining of the body of the digester.

W'hen the lining of the bottom ofthe digester is formed as immediately above described, onezway'in which the) digester maybe built up is by rst putting the plates of the shell together with the exception of the dome. Thenrtheilin'ifng. of the bottom may be4 put in placeand the` sections of the sides placed inside the shell, and the lining of! the dome and the dome itselfv finally: secured imposition.

When the cement lining is made in two layers-,alayer-of cement, lead, or'other suitable material may be interposed: betweensaid cement layers.

place the cement lining directly against thestantially'- uniform size and shape and all laid iatwise with the joints of the inner layer alternating with those of the outer layer, as

-set forth.

2. Apulp-digester comprising a metal shell 'and a carbonized' cement lining composed ofA sections having tongues and recesses at their edges, the sections havingthelr run-er surfaces recessed:` to form packing-recelym g grooves or Iseats adapted? to hold. packings: or: joint-proitectorsr acrossthe` sea-ms or joints formed by lthe sections, asset forth.

In testimony whereof We have signed: our names to this specification, 1nthepresence of two subscribing witnesses, this 16th day of December, A. D. 1891.

CHARLES CURTIS. NATHANEEL JONES. Witnesses:

C. F; BROWN, A. D; HARRISON. 

